1. Field of the Invention
The apparatus of the present invention relates to bulk material transport bags or bulk bags. More particularly, the present invention relates to a bulk material transport bag having a construction which includes baffles on the interior of the bag, so that the bag maintains a relative cubical shape when bulk material has filled the bag.
2. General Background
Dry bulk material is shipped between destinations in large fabric bags, referred to as bulk material transport bags, or in short, bulk bags. Bulk bags, in general, are capable of carrying at least a ton of dry bulk, such as resins or other powdered materials. Generally the bags are formed of fabric material, having four sidewalls, an upper wall, a lower wall, with an inlet spout for introducing material into the bag, and a discharge spout for allowing the material to flow from the bag. The bags, when empty, usually are substantially cubical in shape, and include a lifting loop at each corner so that they may be lifted and moved by forklift. Furthermore, because bulk bags are made of flexible fabric, and they are filled with dry flowable materials, they take the most efficient shape, that of a cylinder. Even though they are made into a square shape, the natural forces of the product force the square into a cylindrical shape. This cylindrical shape creates voids between bags when they are placed into trucks and overseas containers. With some products this loss of space means that the container travels with less than maximum weight allowed. Anytime such a container travels with less than maximum load, shipping costs are unnecessarily high.
In the past, bulk bags were made from a first U-shaped panel of material with two sidewall panels sewn to the legs of the U, and a top portion sewn in to complete the bag. This previous construction requires seams to be in all vertical corners. When baffles are added to this design to maintain the cubicle shape, they are typically attached across the corners. This requires attachment to two separate panels and increased production problems. It is also difficult to attach these panels either before or after the corner seam is to be formed.
One company, Super Sack, Inc. has introduced and patented a bulk bag, under U.S. Pat. Nos. 5,076,710 and 5,165,802, where there is provided six panels of fabric sewn together to form the outer wall of the bag, with the ends of the lifting loops, rather than being attached at the corners, are attached within the four seams of the bag. This patent teaches how to attach baffles to a single panel with reduced labor cost, which create seams in the center of each side. This creates a seam down the center of each side wall of the bag so that stenciling of the company name on the bag wall is difficult due to the passage of the seam.
The shortcoming in the construction of the Super Sack patented bag is that the baffle construction which allows bulk to flow into the space formed by the baffle, by having circular holes cut in the baffle wall, results in stress on the baffle fabric when bulk material is placed in the bag, which results in formation of bulges in the walls of the bag which reduces the space efficiency of the container.
Other prior art teaches the use of baffles within bulk material transport bags, and these are cited in the prior art statement filed herewith.
Other objects of the invention will be obvious to those skilled in the art from the following description of the invention.